diff --git a/frontend/.env.local b/frontend/.env.local
index e720d351..ced57054 100644
--- a/frontend/.env.local
+++ b/frontend/.env.local
@@ -15,6 +15,11 @@ NEXT_PUBLIC_POLYWEATHER_API_BASE_URL=
 NEXT_PUBLIC_SUPABASE_URL=
 NEXT_PUBLIC_SUPABASE_ANON_KEY=
 
+# 必填：生产环境站点 URL（OAuth 回调强制使用此域名）
+# 设置后，所有登录回调将始终跳转到此域名，而非当前浏览器地址。
+# 生产环境必须设为 https://polyweather-pro.vercel.app
+NEXT_PUBLIC_SITE_URL=
+
 # 常用：前端鉴权开关
 # true: 启用 Supabase 登录
 # false: 关闭登录能力，访客模式
diff --git a/frontend/app/page.tsx b/frontend/app/page.tsx
index 02455197..40bd0dec 100644
--- a/frontend/app/page.tsx
+++ b/frontend/app/page.tsx
@@ -1,4 +1,5 @@
 import type { Metadata } from "next";
+import { redirect } from "next/navigation";
 import { DashboardEntry } from "@/components/dashboard/DashboardEntry";
 
 export const metadata: Metadata = {
@@ -7,6 +8,26 @@ export const metadata: Metadata = {
     "PolyWeather dashboard with METAR, MGM, DEB fusion forecast, multi-model comparison, and AI weather decision cards.",
 };
 
-export default function HomePage() {
+export default async function HomePage({
+  searchParams,
+}: {
+  searchParams: Promise<Record<string, string | string[] | undefined>>;
+}) {
+  const params = await searchParams;
+  const code = params.code;
+  if (typeof code === "string" && code.trim()) {
+    const usp = new URLSearchParams();
+    for (const [key, value] of Object.entries(params)) {
+      if (value != null) {
+        if (Array.isArray(value)) {
+          for (const v of value) usp.append(key, v);
+        } else {
+          usp.set(key, value);
+        }
+      }
+    }
+    const qs = usp.toString();
+    redirect(`/auth/callback${qs ? `?${qs}` : ""}`);
+  }
   return <DashboardEntry />;
 }
diff --git a/frontend/components/auth/LoginClient.tsx b/frontend/components/auth/LoginClient.tsx
index 1e97d26c..bcafcaf5 100644
--- a/frontend/components/auth/LoginClient.tsx
+++ b/frontend/components/auth/LoginClient.tsx
@@ -37,6 +37,9 @@ export function LoginClient({ nextPath }: LoginClientProps) {
   const [resetSent, setResetSent] = useState(false);
 
   const supabaseReady = hasSupabasePublicEnv();
+  const siteOrigin =
+    process.env.NEXT_PUBLIC_SITE_URL?.trim() ||
+    (typeof window !== "undefined" ? window.location.origin : "");
   const isEn = locale === "en-US";
   const copy = {
     backHome: isEn ? "Back to Home" : "返回首页",
@@ -136,7 +139,7 @@ export function LoginClient({ nextPath }: LoginClientProps) {
     setLoading(true);
     try {
       const supabase = getSupabaseBrowserClient();
-      const redirectTo = `${window.location.origin}/auth/callback?next=${encodeURIComponent(
+      const redirectTo = `${siteOrigin}/auth/callback?next=${encodeURIComponent(
         nextPath,
       )}`;
       const { error } = await supabase.auth.signInWithOAuth({
@@ -182,7 +185,7 @@ export function LoginClient({ nextPath }: LoginClientProps) {
         return;
       }
 
-      const emailRedirectTo = `${window.location.origin}/auth/callback?next=${encodeURIComponent(
+      const emailRedirectTo = `${siteOrigin}/auth/callback?next=${encodeURIComponent(
         nextPath,
       )}`;
       const { data, error } = await supabase.auth.signUp({